My Orbit 20 tank has been set up since just after Christmas and my 2 moon jellies arrived just under a week ago.

I had been feeding them twice a day using the cubic powdered food. Trying to keep to the "what they can consume in 15 mins" suggestion. They never ate to being completely full as while I was trying to get the powder quantity right feeding them any more than I have been in a sitting resulted in waste food.

It seemed to me that one of them didn't eat as much as the other.

Now today I have discovered one of them has a fairly large radial fold (though other wise seems fairly content as jellyfish go) while watching her, I've noticed a small one form on the second jelly.

The first one is a clear permanent crease in the bell, the second is only visible when she pulses.

Reading that the folds could be down to malnutrition I've just fed a small amount again. Though I am also questioning the flow of the tank now, as while most of the time they pulse happily in the middle of the tank they seem to like swimming to the side of the tank then "riding the flow" around the tank edges.) I've turned the flow up a little faster but I'm wary of going to fast.